Clinical Laboratory

The laboratory has a central area where specimen are received and logged. Those requiring separation are centrifuged and the plasma/serum separated for analysis or storage. Samples for storage are processed and kept in deep freezers (-35^oC and below).

The Clinical Chemistry unit has been equipped with the Vitalab Selectra E Clinical Chemistry analyzer (which is a fully automated analyzer with a throughput of 270 tests per hour), the Humalyzer Junior Photometer (a semi-automated chemistry photometer) and the Combilyzer Plus Urine Chemistry analyzer. The unit currently performs a wide range of assays including renal function tests, liver function tests, lipids, glucose, uric acid C-reactive protein (CRP), ferritin and urine chemistry. An ELISA microplate reader and washer are also available. Depending on the specific laboratory requirements of projects, several other tests can be performed, e.g. hormone assays, etc.

A staff has had a 3-month training in High performance liquid chromatography (HPLC) techniques for assaying retinol at the Department of Nutritional Sciences, University of Wisconsin, Madison, U.S.A. It is envisaged that, an HPLC machine will be acquired so that, the analysis of micronutrients and other substance can be performed at the Centre.

The laboratory performs the 18-parameter complete blood count (CBC) with 3-part differential analysis using an automated Haematology analyzer, the ABX Micros 60. The analyzer has a throughput of 60 samples per hour. Glucose-6-phosphate dehydrogenase (G6PD) tests, both qualitative and quantitative, are also performed using a water bath and a spectrophotometer. Hemocue readers are also available for determination of haemoglobin in the field.

The microscopy unit is equipped with two microscopes. Presently, the main test performed in this unit is the examination of thick and thin blood smears for malaria parasites. The thick smear is used for quantification of parasites whiles the thin smear is used for parasite identification. Between December 2003 and December 2004, more than 10,000 blood smears were examined in this section. At least 10% of the slides examined were sent to the Noguchi Memorial Institute for Medical Research (NMIMR) for quality checks. The level of agreement between the blood smear readings from the two laboratories was excellent

Work in the PCR unit started following transfer of the technology from the London School of Hygiene and Tropical Medicine (LSHTM). A staff underwent a two-month training in PCR techniques at the LSHTM. The unit has a sterilizing work station, a thermal cycler with its accessories and a gel documentation system. Analyses carried out in this unit include:

• Molecular genotyping for the determination of resistance of malaria parasites to commonly used anti-malarials (chloroquine and amodiaquine) using gene markers, pfcrt and pfmdr1.
• Merozoite surface protein 2 (MSP2-block 3) polymorphisms to distinguish recrudescence from re-infection.
• Determination of seasonal dynamics of MSP2 (block 3) multiplicity of infection (MOI) of P. falciparum in infected individuals.

Currently, the technology for sulphadoxine-pyrimethamine (SP) genotyping to determine resistance of malaria parasites using gene markers Pfdhfr and Pfdhps in infected individuals is not available. It is hoped that, this technology will also be transferred from the LSHTM in the not too distant future.

Another staff is on a 6-month training in molecular techniques for the investigation of haemoglobinopathies at the Berlin Institute for Tropical Medicine, Germany. Thus, this technology will also be available in our laboratory after his return.

Entomology Unit

The Entomology unit has CDC light traps for catching mosquitoes from the field, a dissecting microscope for identification and sorting of mosquitoes. Determination of circumsporozoite antigens in the mosquitoes is performed by ELISA method using an ELISA microplate reader. From the ELISA results, the entomological inoculation rate (EIR) is calculated.

Legs of the Anopheles gambiae mosquitoes have been preserved and would be used for:

• Anopheles gambiae complex determination and
• Determination of the prevalence of knock-down-resistance (kdr) gene (e.g. pyrethroid resistance) in the mosquitoes.

In addition to the standby electricity generator at the Centre, the laboratory has a 10 kVA UPS/Stabilizer. All sensitive laboratory equipment such as the thermal cycler, clinical chemistry and haematology analyzers have been hooked onto this UPS/Stabilizer to ensure that analysis is not disrupted at any time due to power outage.

A new water distillation plant has been installed. With a distillation rate of 3.5 liters per hour, this plant now distills all the water needed for the laboratory’s activities. This means distilled water no longer has to be brought from outside.

Contact: David Kwame Dosoo